The present invention is directed to a tubular mold, which can be positionally fixed at a top end in a water tight manner within a water tank, as well as a method for recalibrating a tubular mold that has already been in use.
It is generally known that tubular molds used for continuous casting are positionally fixed in an impervious manner in water tanks used for cooling. To withstand the high cooling-water pressures, the tubular molds are reinforced at their upper ends, to enable them to retain their inherent stability. In this connection, it is generally known, especially when working with xe2x80x9cbeam-blankxe2x80x9d or xe2x80x9cdog-bonexe2x80x9d molds having a double T-shaped cross-section, to weld wedges (i.e., splines) into the mutually opposing outer channels at the upper ends, to provide tubular molds of this kind with a substantially rectangular cross-section (as seen via a frontal view).
In recalibrating these types of tubular molds, using the explosive reforming method (Accumold method), the use of welded-in wedges has proven, however, to be a hindrance during the reforming process. In addition, the welded seams sometimes tear apart, resulting in an imperfect seal. Furthermore, it became apparent that it was impossible or very difficult to recalibrate the original form at the upper end of the tubular molds.
The present invention first provides a tubular mold that can be positionally fixed, in a reliably impervious and form-stabilized manner, in a water tank. Second, to provide a method for recalibrating a tubular mold which has already been in use, the invention provides a method which allows the tubular mold to be repeatedly reworked without causing sealing problems or mold material damage.
According to the invention, an outer peripheral groove having, in particular, a rectangular cross-section, is provided at a distance from the top front end of the tube wall of a tubular mold. Furthermore, a circumferential recess is formed adjacently to the top front end of the tubular mold. This recess is used to ensure that the reinforcement frame, which supports itself on the flange of the water tank as well, is sealingly located in position with an exact fit. The reinforcement frame is also sealed off from the water tank. Disposed underneath the reinforcement frame are two U-shaped flanges having inner latching segments, which grip from opposing sides into the peripheral groove on the tube wall.
The radial extension of the latching segments is smaller than the depth of the peripheral groove. Once the U-shaped flanges are positionally oriented with the aid of the latching segments in the peripheral groove, the reinforcement frame is slid onto the recess and then securely fastened by screws to the two U-shaped flanges. In this way, the top end of the tubular mold is provided with sufficient dimensional shape stability with respect to cooling-water pressures. This obviates the need for welding, thereby eliminating the danger of damage to the mold material.
If a tubular mold that has already been in use requires recalibration, one merely needs to remove the reinforcement frame and the U-shaped flanges. This makes it possible to restore the inner mold cavity, so that it meets the continuous casting requirements. Once the mold cavity has been restored, which, as a rule, is associated with a reduction in wall thickness at the top end of the tubular mold, the recess is merely reworked in conformance with the reduced wall thickness. A new reinforcement frame, adapted thereto, is then put in place and screwed to the remaining U-shaped flanges. These flanges can remain because the radial extent of the latching segments is smaller than the depth of the peripheral groove.
The fact that this calibration process can be repeated numerous times and that merely the appropriate reinforcement frames need to be provided is quite beneficial.
In accordance with one advantageous specific embodiment, the inner rim of the reinforcement frame facing the deepest part of the recess is provided with a hollow recess to accommodate a sealing ring. This sealing ring is pressed into the corner region of the recess when the reinforcement frame is screw-mounted on the U-shaped flanges, thereby ensuring the sealing action.
The features of the invention can be applied quite advantageously to a tubular mold configured with a double-T shape, as is generally known, for example, in the form of a xe2x80x9cbeam-blankxe2x80x9d or a xe2x80x9cdog-bonexe2x80x9d mold. It is also within the scope of this invention that it be applied with billet and bloom shapes.
All known methods can be used to restore the inner mold cavity of a tubular mold. Particularly advantageous, however, is the explosive reforming method, in which a mandrel is introduced into the tubular mold. Once the inner mold cavity is restored, the recess at the top end of the tubular mold is advantageously reworked in a milling operation.